BLOOD FLUKES Flashcards
cause intestinal, hepatosplenic, pulmonary, urogenital, cerebral and other
schistosomiasis
the only fluke with separate sexes. The female worm lies in the gynecophoral canal of the male.
schistosome
There are five medically important species:
- Schistosoma mansoni:
- Schistosoma haematobium:
- Schistosoma japonicum:
- Schistosoma intercalatum:
- Schistosoma mekongi:
causes intestinal schistosomiasis.
Schistosoma mansoni
Schistosoma japonicum
Schistosoma intercalatum
causes vesical (urinary) schistosomiasis.
Schistosoma haematobium
causes intestinal schistosomiasis. This seems to cause milder disease in man. It causes disease in other vertebrate hosts.
Schistosoma mekongi
This species lives in the veins of the intestine. Geographical distribution: It is found in Africa, South America, Middie East (some Arab countries) etc. Stream and lake-based transmission is common.
Schistosoma Mansoni
The snail hosts that harbor S. mansoni are the genera:
Biomphalaria (B. glabrata) and Trobicorbis.
The worm lives in the veins of the bladder of humans. The peak prevalence is the 10-14 year age group.
Urinary Scistosomiasis
Urinary Scistosomiasis
Etiology -
Schistosoma haematobium
The snail hosts that harbor S. haematobium are the genera
Bulinus (Bulinus africanus, B. truncatus) and Physopsis.
The female adult worm lays about 500-3500 eggs daily. The eggs are ovoid, bearing only a minute lateral spine
or a small knob postero-laterally. It is found in Japan, China, and Philippines, etc.
Schistosoma Japonicum
This is the rarest and least pathogenic schistosome that matures in man. It is found in Western and Central Africa.
The daily egg output is about 300. The eggs have a terminal spine.
Schistosoma Intercalatum
schistosomes infective stage
Cercarae released by snail into water and free-swimming
schistosome diagnostic stage
schistosome in feces/urine
Laboratory Diagnosis
1. S. mansoni:
Microscopic examination of the stool for eggs after concentration by sedimentation
method. The egg has characteristic lateral spine. Rectal snip
Laboratory Diagnosis
2. S. haematobium: m
Examination of the urine after allowing it to sediment in a conical urinalysis glass. A drop from the sediment is taken and examined for eggs. Egg has terminal spine. A biopsy from bladder
schistosome treatment
praziquantel
schistosome prevention
- Health education:
A. On use of clean latrines and safe water supply
B. Avoid urination and defecation in canals, avoid contact with canal water - Snail control:
A. Physical methods:
i. Periodic clearance of canals from vegetations. ii. Manual removal of snails and their destruction.
B. Biological methods: Use of natural enemies to the snails such as Marisa.
C. Chemical methods: Molluscides are applied in the canals to kill the snails. e.g. Endod
the smallest splayed worm that preys on humans (0.5 - 0.3 millimeters). Infections have been reported in Kuwait, and the worm lives in the small intestine of the human being buried between the Intestinal villus. It also lives in the intestines of some animals that feed on fish such as dogs and cats.
Heterophyes heterophytes
Heterophyes heterophytes infective stage
Host becomes infected by ingesting undercooked fish contaring metacercariae
Heterophyes heterophytes diagnostic stage
Embryonated eggs each with a fully developed mitacidum are passed in feces
Opistorchis
Causal Agents
Trematodes (flukes) Opisthorchis viverrini (Southeast Asian liver fluke) and O. felineus (cat liver fluke).
Opistorchis infective stage
Metacercariae in flesh of skin of fresh water fish are ingested by human host
